Vehicles like mining loaders may require that the drive line, and the engine in particular, be positioned as low as possible, either in order to present a height as low as possible and/or to present a low point of balance.
Thus, prior art suggests that the engine be positioned generally in line with the rest of the drive line, resulting in a low position of the crank shaft. It might be the case that the vehicle has a wheel axle located between the main transmission unit and the engine, thereby forming an obstacle that prevents the crank shaft from being directly connected to the main transmission unit. However, this problem is overcome by means of a second transmission unit that is connected with the crank shaft on one hand and with the main transmission unit via an intermediate drive shaft on the other hand. The intermediate drive shaft is offset in relation to the crank shaft and to the wheel axle by means of the second transmission unit and, accordingly, connects the crank shaft indirectly with the main transmission unit.
According to prior art, the second transmission unit comprises at least two interacting cog wheels arranged in a casing, a first of said cog wheels being connected to the crank shaft and a second thereof being connected to the intermediate drive shaft. This unit is heated during operation, and, therefore, there may be required a separate cooling circuit that provides the second transmission unit with a cooling liquid that is circulated through said casing. The use of a separate cooling circuit adds to the total cost of the drive line and requires a separate handling thereof in connection to service and repair work. Normally, the cooling liquid is oil that needs to be changed at predetermined intervals.